Beast of burden

By Bob Cervi

Published Friday, June 20, 2008

In the 150th year of the diesel engine, a German factory where it all started produces the technology on a huge scale.

You wouldn't normally expect to find a shrine, replete with wreath and flowers, in a corner of a huge, noisy factory. However, such a shrine does exist. This particular monument marks an important point in the history of engineering. No matter that the flowers are plastic and the wreath is made of metal. The epitaph above the shrine, written in German, says it all: "This is the place where Rudolf Diesel developed the first [diesel] engine, 1893-97."

The German factory is the MAN Diesel plant at Augsburg, west of Munich, where some of the world's biggest diesel engines are made for marine vessels. MAN's roots in the country go back even further, some 250 years, but it is the 150th anniversary of inventor Rudolf Diesel's birth that the company is marking this year.

Rudolf Diesel, born in 1858, at first had difficulty convincing the world of his brilliant idea for a 'rational heat engine' in which a piston compresses - and thereby heats - air in a cylinder to such a degree that the addition of a small amount of fuel triggers an explosion that drives the engine. The key advantage of this type of engine is low fuel consumption. But no one at the time accepted Diesel's contention that the mechanism could create a high enough level of pressure for it to work.

However, Heinrich von Buz, director of MAN predecessor Maschinenfabrik Augsburg, decided to give Rudolf Diesel a chance. Help also came from the Krupp company, a cannon builder that was able to provide a cylinder casing that was able to withstand huge pressure. Over a four-year period the 'Diesel patent heat engine' was successfully developed, and Diesel subsequently took the technology all over the world.

For MAN's predecessor companies, the tie-up with Rudolf Diesel helped to engender a long history of engine production. Today, MAN, which is perhaps better known for making trucks, claims to be the global leader in the market for large diesel engines.

The Augsburg engine factory, however, does not make the very biggest of the diesel engines produced by MAN. Augsburg manufactures the more compact four-stroke engines. Their bigger, two-stroke cousins are assembled under licence around the world, but mainly in the Far East. Components for these licensed engines are supplied by MAN's Danish plant in Copenhagen.

Big beasts

MAN lays claim to providing the world's biggest diesel engines, the two-stroke, 115,000-horsepower beasts that are used in the largest container ships. But these are so massive that they have to be assembled in the shipyards where the vessels are constructed - in Japan, South Korea and China.

In one sense, MAN is a victim of its own success. "Nearly every container ship that's built is bigger than last one, so we're having to make engines bigger and bigger," says Jonathan Walker, technical spokesman at Augsburg. But, he says, the engines do have a maximum size - they don't go any bigger than 14 cylinders long because of the limited size of the engine rooms they occupy. Container ship companies may have to consider fitting two engines for future, bigger ships.

The engines are used not only to power ships. Four-stroke engines are fitted in power stations around the globe, although some Greek and Indonesian islands have the bigger two-stroke engines, which have to be reassembled at the power stations.

At Augsburg, production is on a huge scale. The engines, which come in at 300-400t and are roughly the size of a small house, are surrounded by hoists, which lift the numerous heavy components that are carefully hand-fitted by specially trained workers. There are also large sunken assembly floors looking like meteor craters, contributing to an overall impression of a James Bond film set.

It takes several weeks to build and finish each engine at the plant, and one engine is shipped roughly every second day. That's up to around 150 engines a year. The labour-intensive plant employs over 3,000 people.

MAN started life as a German ironworks in 1758, and the Augsburg plant carries on the tradition by operating its own foundry to produce the huge cast-iron blocks that form the engine frames. Massive bolts are run through the frames vertically and horizontally to strengthen them prior to the fitting of components that are largely made and finished at the plant using automated machining processes.

Turbocharged

The plant also makes turbochargers for engines produced at Augsburg and at other MAN diesel factories. All large diesel engines have used turbochargers for the last half century. The turbochargers are also hand-assembled, and their huge blades have to be made to aircraft-industry standards, Walker says.

When an engine is fully built it undergoes tests that include eight hours of continuous operation. Transporting them out of the plant is a major operation. "For the larger engines, a whole task force has to go out and take down overhead cables and pilot low-loaders under bridges to the motorway," Walker says.

Ironically, Augsburg is not ideally positioned geographically for producing marine engines, Walker confesses. "Engines are needed at sea, and we're on the wrong side of the European watershed. We're on the Danube side, and we have to get engines to the Rhine-Rhone side for shipment globally."

It is partly because of this that MAN is restructuring its engine production in the next few years. Augsburg's output of larger four-stroke engines will move to other plants at the end of this decade, leaving it to concentrate on smaller four-stroke engines and components - growing demand for which, says Walker, will more than pick up the resultant slack at Augsburg.

The MAN diesel engine plants taking on work from Augsburg will be those at Frederikshavn in Denmark and Saint-Nazaire in France. The company has also a recently-opened engine assembly facility in India at Aurangabad, and turbocharger facilities in the Czech Republic and China. In the UK, MAN operates a global maintenance and repair facility in Stockport.

Greener future

The future for the MAN Diesel division as a whole is very much tied up with new technology, and most particularly greener engines, Walker says: "We see the diesel engine as part of the solution to global warming. For example, if all electricity produced by combustion engines were produced by diesels, there would be at least a 20 per cent saving in energy compared with large steam and gas-turbine power stations. Diesel engines have high efficiency and low emissions per KWh of work done."

However, increasing the efficiency of these engines comes at a price. If you want decreased fuel consumption you've got to have higher temperatures in the engine's combustion chamber; and with higher temperatures come higher emissions of nitrogen oxide (NOx). In other words, there is a trade-off between reduced fuel consumption and increased emissions.

But, says Walker, MAN is aiming to beat this trade-off: "One of the great hopes for fuel consumption in the future is two-stage high-pressure turbocharging. We reckon we can get about a 30 per cent reduction in NOx without affecting efficiency by exploiting the 'Miller Process'.

"This process involves closing the inlet valve earlier, allowing the intake of air to expand and cool and thus reduce the temperature peaks which cause the most NOx formation. High-pressure turbocharging helps us compensate for early closing of the valve."

Walker also points to other green measures being looked at, including marine technology that uses sea water as a combustion-process coolant: "We have bought and are developing humid air motor [technology]. Sea water is turned to vapour that then enters the [engine] cylinder to cool combustion and reduce formation of NOx. The sea water is evaporated into the charge air and leaves behind the salt, so that no salt enters the engine.

"We are also now introducing 'common rail' on our four-stroke diesel engines. Common rail enables us to have maximum injection pressure at all engine speeds and under all load conditions, which means we can exactly match the amount of fuel injected to the amount of power needed, and this means we get much cleaner combustion right across the engine's operating profile, not just at full load.

"We also have new dual-fuel engines for liquid natural gas tankers. Because of the movement of the tanker and the outside temperature, a certain amount of the liquid natural gas evaporates, and we can use it as a fuel in the engine."

A wide range of liquid and gas fuel can be burnt in MAN's diesel engines, he adds. "We can burn vegetable oil and even rendered animal fats. We even have a power plant that runs on all the chip fat that's used in Tyrolean restaurants [in Europe]. This is one of three plants that produce a further renewable fuel in the process."

MAN clearly has no intention of resting on its historic laurels. It does, after all, face major competition from the world's other leading maker of big diesel engines, Wärtsilä of Finland. The German company claims to hold an 80 per cent global market share of the biggest, two-stroke engines for marine vessels, and is one of three major players in the four-stroke engine market.

Under today's healthy market conditions, Augsburg continues to enjoy strong demand for its massive products, and has seen production increase by over 10 per cent in recent times. Were Rudolf Diesel to return to the spot in Augsburg where he developed his first engine, he no doubt would be amazed at the overwhelming uses to which MAN and other manufacturers have put it. He would also have a chance to appreciate the contribution that his invention has made to modern technology.